Gate valve

ABSTRACT

An air lock and metering gate valve in which upper and lower arcuate blade-type gates are pivotally mounted on the housing in spaced-apart relation defining a space into which flowable material is admitted and discharged. The gates are operated in sequence so that only one gate is open at any time. Piston motor are direct connected to each of the valve blade arms and the upper blade is spring biased to the closed position to assure that it closes first and opens last. Effective seals are provided for sealing each blade with respect to the valve housing, and a pneumatic piston motor control system permits uninterrupted sequential filling and emptying of the valve housing at adjustable rates.

United States Patent- George W. Armstrong Inventor FOREIGN PATENTS c/o 0. Armstrong & 553112, 284 E. Dayton 67 287 3/1945 Denmark 222/448 Drive airbom 0 i0 4 4 50,499 9 1966 G [21] Appl. No 755,274 many 222/450 [22] Filed Aug. 26, 1968 Primary Examiner-Robert B. Reeves [45] Patented Jan. 19,1971 AssismntExaminer- Hadd S. Lane Attorney-Marechal, Biebel, French and Bugg [54] GATE VALVE l2 Chums 11 Drawing Flgs' ABSTRACT: An air lock and metering gate valve in which [52] US. Cl 222/445, upper and lower arcuate blade-type gates are pivotally 222/449, 222/5 4 mounted on the housing in spaced-apart relation defining a [51] Int. Cl. G0lf 11/28 spacg into which fl abl material is admitted and [50] Field of Search 222/445, discharge The gates are operated in Sequence so that only 504,448 450 one gate is open at any time. Piston motor are direct con- 6 R f d nected to each of the valve blade arms and the upper blade is [5 1 e erences spring biased to the closed position to assure that it closes first UNITED STATES PATENTS and opens last. Effective seals are provided for sealing each 1,639,517 8/1927 Lassen 222/450X blade with respect to the valve housing, and a pneumatic 2,439,861 4/1948 Pootjes.... 222/445 piston motor control system permits uninterrupted sequential 3,257,045 5/1966 Carpentier 222/504X filling and emptying of the valve housing at adjustable rates.

o 55 e 64 22 32 O 428 I8 33 y I l H. 9a 2 40 Q 32 5 x 16 t o G SHEET 2 OF 3 FIG-6 FIG-5 FIG-#4 PATENIED JAN 1 9 I97! SHEET 3 OF 3 FIG =2 FIG-9 .operation. i The blades are p :1. my I H "oxrsvstveg; I

. Airlock type valves are used for discharging andoften' measuring flowable particulate material, suchias powders; grains. chips or the like, into a'controlled' environment, such as into an arealofpressure difference; for exampIeQan air conveying system or the like, where a straight through openingQwould upset pressures in the systemor otherwise would not permit the material'toflow. Com'mdnly'rotary gates, or rotors having buckets orpockets are, employed. requiring close tolerance I machining on the-Side. walls and cavity. Where corrosion resistant materials are.tequired.asuch asst'ain'less steel. the cost of such valves becomes-high. Further sin such rotary designs. the edges of thewbucke'ts pass through points of shear as many times for each revolution as there are b'uckets, which causes high power consumption and wear.

These and other objects and advantages of the present invention will become apparent from'the following description. I

" The present' invention utilizes blade valve conceptsto' pro- I vide an air loclt valve which is simple in designandyet effec tive in operatiomSheer-mctal materials may be'used for' the valve housing} the moving-blades. e ema; other metallic 1 parts. This 'substan'tially'reduces the 'cost bfthe valve over that of designs which rotary delivery devices.

' valve-:h'ous'ingis provided which is incross section andon which are mounted-upper" and lower curved. blades. These '-blades eachmove-through suitably j sealed openings in one wall of thevalve'housing into flow per;

A simplified arrangement is provided for operat ng blades and includespivotallymounted blade supportarms and vironment. Further. it is inherent in' the design that the valve is essentially-jam-proof, in that ovcrsized; or foreign'articlcswill not interrupt thecycle of operation. For. example, if a foreign object enters suchas to hold one blade partially open, the cyclewill continue and on the next cycle. the foreign object will simply fall on through as the blade opening enlarges.

A further advantage issimplicity of construction and the fact that relatively inexpensive materials can be employed as comparedto conventional rotary valves. No close machining isrequired for the parts. such as is required for the sidewalls and flcavities of conventional rotary va'lvesj-urther the valve of j {this invention haslow power eonsumptionfand, for any given size. can handle more material than its rotary counterpart. lt

can be used for metering and measuring materialand for controlling the flow of material even where there .is no pressure differential.

the accompanying drawings and the-appended claims.

BRIEF DESCRIPTlON OF THE DRAWINGS FIG. l is a perspective view of a valvc constructed accordof the p'arts'in a moved position; I I FlG. Jisa'view similar to FIG. gbut enerallyiectangular ha Qppqsite side; v

Y fluid pressure "operated piston-motors which areflireetly connected'to such ar'rns: The' -pistoit motors e arrangedso that I while an opening force is being applied'to one arm; a closing force is simultaneously applied to theiopposite arm. lnjthis manner, two-way'piston motors-may beyemployed for the bias isiapplied 0 one of the blades to assure proper sequential tioned exteriorly of the housing so that they do not interfere with the movement of material within the housingi Further,

V the blades are each curved arcuately andm'ove along a corresponding arcuate path. The upper blade has its concavity facing downwardly in such a manner that the weight of the material against its upper surface actually assists in the closing of the blade.

Effective seals are provided for each ofthe valve: blades.

This includes seals which engage the curved upper surfaces of f the blades at'the housing sidewalls and seals which engage the. upper and lower blade surfaces at the blade slot. The latter seals are preferably mounted 'exteriorly of the housing and systernl r'eferably"mountedon arms which'are' posibody 12 is generallyrectanguiar in section; and defines at its l wsrt a s l l i w t HQ. 9 is enlarged vertical section through a fragment of the rearwa'll showing one' of the blade slot scaling arrange,

sequential'opcning and 'closingof the'valve blades-A- spring irigto this invention; h v s h I FIG. 2,is .a side elevational view of the valve showing some FIG. $1.15 and 6 'are diagrams showing the sequentialopem ,tionoftheyalvepv v FlG. 'l a" vertical partially broken awaysectiontaken f through one valve body,showingthe'details of the upperand.

a. fragmentary vertical section taken generally DEStfRlPTlON 0F Tire PREFERRED'IEMBYODIIMENT Referring-tothe FIGS 1 of drawing illustrates a preferred'embodiment of the invention. rotary blade air lock valves-is illustrated generally at 10. in FIGS. L-Z and 3 as including an elongated sheet metal housingor body l2. The

upper end an inlet 13 and at its lower end an outlet 14. The

' rectangular housing or body 12 maybe considered as having a front wall 15. a pair of opposites side walls 16 and 17, and a rear wall l8. I v v I The upper end of the housing 12 at the inlet 13 is formed with a peripheral outwardly extending flange indicated generally at .20. The side portions of the flange 20 extending along the sidewalls l6 and 17 are formed as generally L- may'be 'readily'remov'ed and replaced without thenece'ssity for disassembling the valve.

A fluid motor control system is provided which permits full automatic operation of the valve iri'a-cycle of operation so that the upper blade is first opened to-let the material in and then closes before the bottom blade opens to let the. material out. Av control valve is reversed by the actuation of either one of a pair of pilot valves sensingthe open position of each respective blade. The rate of blade movement in a cycle of operation may be accurately regulated by controlling the rate of fluid exhaust from the motors. I a

The arrangement has several important advantages. First.

shaped bracket members having downwardly depending side flanges 22 engaging the outer surface ofthe housing side walls.

Similarly, the lower endvof the body [2 .at the outlet. is

' formed with a'peripheral mounting fla'nge 25 and upwardly extending flange portions 26 at the sides for attachment to the sides of the body [2. v

The. valve 10 includes a pair of curved bladeswhichare each pivotally mounted on the housing and are positioned to Y extend through the rear wall 18 into flow blocking relation to the passage or conduit defined within the housing 12, Thus.

the valveincludes an upper flow control blade 30 which is preferably formed of sheet material and is rolled or-otherwise since fluid pressureis used for actuation, the air lock valve of.

this invention maybe used in an explosive or hazardous ensuitably formed .into a true arc orportions portion of a cylinder, with the concavity thereof facing downwardly. The upper blade 30 ispivotally mountedjori the housing 12 by means of a pair of external support arms 32, there being one showingthc valve from l a aflai'tge"adapter for of theinvention as a substitute. for valve's using a' circular connecting flange; and h h FIG. ll. is simplified pneumatic diagram of the control each of the arms 32 pivotally mounted adjacent each of the sidewalls l6 and 17 respectively. The upper ends of the arms 32 are curved or turned inwardly toward each other at 33 and attached. as by spot welding. to the underneath surface of one end of the blade 30. The lower ends of each of the arms 32 are pivotally mounted on supports 34 extending into the lower flanges 26. as shown in FIGS. 2 and 3.

The radius of curvature defined by the arms 32 substantially equals the radius defined by the blade 30 so that the blade tends to move along a true arc. However. the blade 30 may be arranged to move along an are which gives the blade camlike upward closing or sealing movement. in the manner disclosed for the blade in U.S. Pat. No. 3.380.475. The blade is formed with a width which substantially equals the width of the housing 12. and has a sufficient length so as to extend in the closed position as shown in FIG. 2 from the inside surface of the front sidewall 15 across the valve and through a suitably formed blade slot 35 formed in the back wall 18 for at tachment externally of the housing to the arms 32. While inside arm support for the blade 30 is not disclosed. such may be provided if necessary to support the weight of the material on the upper blade. or for connection in the manner taught in US. Pat. No. 3.380.475.

The invention further includes a lower arcuate blade positioned adjacent the valve outlet 14 and mounted for pivotal movement on the housing 12. including a sheet metal blade supported on a pair of arms 42. The blade 40 is formed similarly to the blade 30. and preferably of the same material. and is supported with the concavity thereof facing upwardly. For manufacturing purposes. the blades 30 and 40 may be identical in construction. The arms 42 are pivotally mounted at supports 44 on the upper flanges 22 and are slightly offset so as not to interfere with the movement of the arms 32. The blade 40 extends through a sidewall slot 45 (FIG. 7) in the wall 18 similar to the slot 35 provided for the blade 30. The blades 30 and 40 thus define with the housing 12 an enclosed space of constant or predetermined volume by means of which dry or particulate flowable material may be metered and measured, and emptied through the outlet 14 into an area of pressure difference as compared to that of the inlet 13.

The valve of the present invention further includes fluid pressure controlled motor means interconnecting the blades 30 and 40 and providing for alternate movement thereof between flow permitting and flow blocking positions with respect to the valve housing, thus providing sequentially for the filling of the defined space within the housing followed by the emptying of material from such space. For this purpose. the motor control means includes a pair of piston air motors 50. one each being positioned adjacent each of the sidewalls 16 and 17, for fully balanced operation ofthe valve blades.

The piston motors have their opposite ends connected to the arms 32 and 42 in such a manner that when a closing force is applied to one of the blades, an opening force is applied to the other blade. For this purpose, the piston rods 52 are con nected at pivotal bushings 53 to the arms 32 at positions between the pivot supports 34 and the blades 30 so that extending movement of the rods 52 applies an opening force to the upper blade 30. At the same time. the clevices 55 of the piston motors are pivotally attached to the arms 42 on rearwardly extending and downwardly offset arm portions 420. The motors 50 are thus connected to the arms 42 at points remote from the pivot supports 44, so that extension of the motor rods 52 applies a closing force to the blade 40.

The invention includes spring bias means for assuring that the upper blade 30 always closes first and opens last. as compared to the movement of the lower blade 40. For this purpose. a separate tension spring is positioned adjacent each sidewall 16 and 17 of the valve 10, and has one end connected to a binding post 62 and has the other end connected to one of the arms 32 adjacent the pivotal connection 53 of the piston motor 50, and urges the movement of blade 30 into the closed position. The combined force of the springs 60 is sufficient to maintain the blade 30 in the closed position until the blade 40 has been fully closed by the first portion of the stroke of the piston motors 50. Once the blade 40 reaches its closed position. continued extension of the pistons 50 result in the opening of the upper blade 30 against the retractivc force of the springs 60. The blades are closed in the reverse manner. the springs 60 assuring that the upper blade 30 closes before the lower blade 40 is permitted to open. Angle iron stop pieces 63 and 64 engage respectively the arms 32 and 42 and define the fully open positions of the blades 30 and 40. The closed posi tion of the blades is defined by the blade engaging the inside surface of the front wall 15.

The valve of the present invention is provided with effective seals for sealing the blades at the slots 35 and 45 as well as for sealing the blades at the sidewalls l6 and I7 ofthe housing 12. Reference may be had to H65. 7 and 8 for details of suitable soft sidewall seals which may be employed in the present invention. Referring first to the sidewall seals associated with the upper blade 30, a pair of plates 70 are received within the housing inlet and retain an elastomeric seal member 72 which has a lower blade conforming edge 73 protruding or extending below the plate 70. The plate is retained in position on the sidewall by a series of screws 74. Since the exposed lower portions 73 of the seals 72 conform generally to the curvature of the upper surface of the blade 30. they engage the upper blade surface in the closed position of the blade and effectively seal the blade at the respective housing sidewalls.

The lower blade 40 may be sealed within the housing in somewhat the same manner. as provided by lower plates which have curved lower surfaces and which support elastomeric seals 82 against the respective sidewalls of the housing. ln this case. the lower edges 83 of the seals 82 project below the retaining plates 80 by a short distance and are curved to conform to the curvature of the upper surface of lower blade 40. The upper end 85 of the plates 80 may be curved inwardly toward the sidewall as shown in FIG. 8. to prevent the accumulation of material.

The slots 35 and 45 within the rear wall 18 are preferably fully sealed with seals constructed in the manner shown in FIG. 9. An upper flexible seal extends the width of the slot 35 and is proportioned to extend through the slot into overlying relation with the upper surface of the blade 30. A backup retainer or support 92 extends partially into the slot 35 and prevents the seal 90 from rolling outwardly through the slot during opening movement of the blade. The upper seal 90 is formed with an inner abrupt or sharp edge 94 which engages the upper surface of the blade 32 and. during opening movement of this blade. is in scraping and wiping contact with the upper surface.

An outer upper blade seal 96 is also formed of flexible strap material and extends oppositely to the seal 90 to prevent the entry of air or foreign material into the interior of the housing. The seal 96 extends outwardly of the blade 30 and has a lower end positioned in overlying relation to the upper surface of the blade. A retainer plate 98 removably retains each of the seals 90 and 96 against the outer surface of the rear wall 18 and is accessible from outside the housing for the replacement of the seals. as necessary.

It is also desirable to seal the lower surface of the blade 30 to prevent the escape of the material as well as to prevent loss of pressure differential. and for this purpose. a lower flexible seal 100 extends from a position outside the housing 12 through the slot 35 and engages the lower surface of the blade 30 with a wiping action. Similarly, an outside seal strip 102 extends outwardly of the seal 100 and engages the lower surface of the blade 30. The strips 100 and 102 are retained by an external retaining plate 105. and may be readily replaced without disassembling the valve. The valve wall 18, at the terminal ends of the slots 35 and 45. isprovided with outwardly extending tab members H0 which engages the vertical edges of the seals 90. 96. 100 and 102. to provide for a complete seal at the slots and to prevent bypass of material or pressure around the ends of the seals.

'I'he lower blade 40 may be provided with identical seal structure at the; slot as described above for the blade 30. and in fact suchscal'parts associated with each blade'are preferably interchangeable with corresponding parts associated with the other blade. While the bladeslot seals are preferably located exteriorly of the housing as previously. mentioned. it is within the scope ofthe invention to'locate the seals on the inside surface in the 'manner shown in US. Pat. No. 3,380,475. The arcuate inside bla'de seals 72 and 82 are subject to very little abrasive wear and thus require a minimum of attention.

FIG. illustratesthe mannerin which the valve may-be provided.'at each of its inletand outlet ends. with a circular mounting flange 115.5 Circular flanges I may be provided in lieu of either orbothfof the rectangularly arranged flanges or 25. In particular. the valve of this invention may be readily adapted asa direct replacement for rotary air lock valves 6 parts as shown in'FlG 4' is attained with the opening f the pilot valve la by the rod I28. i I

The rate of automatic opening and closing of the blades and 40 can be accurately controlled by controllingtherate of exhaust from the piston motors 50. For t'hispurpose. the valve 120 has a common exhaust port I; and an adjustable restrictor I32 at the port 130 controls the rate of movement of each of the blades by controlling the rate of exhaust from the piston motors. An important advantage of this arrangement is that the valve can thus be accurately regulated and adjusted after installation, and can be "tuned"- to the system to obtain the maximum delivery rate or any desired delivery rate less than 7,

maximum. In this manner. theweight and flow characteristics ofthe material being controlled can be accountedfor to obtain the greatest use and benefit of the valve by accurately' controlling therate of movement of the blades after'installation. In addition, it is within the scope of the invention to providc separate exhaust for both ends of the motors 50 so that the speed of movement in one direction can'be controlled independently of the speed of movement in the other direction. where desired.

'lt is accordingly seen that a versatile. simple. and dependable airlock valve is provided. lt is a valve which cannot easily 25 .the'blade 30. a mechanical lorce'will merely .be applied to the v be jammed.- For example. if an obstacle prevents the closing of blade 40just as if the blade 30 had reached its predetermined required. Nonnally. double acting f-pneumatic} motors are preferred since simple open end exhaust systems can then'be used. supplied from a-lowi cost air compressor. A suitablevalve control'system is shown in FIG, I0 as including aitwoposition. two'way spool-type .valve .120. 'The valve'spool may be moved. in either of its two selectable. positions to apply air under pressure-to'each of theftwo-way'reversible piston mo-- tors 50, and may be constructed according to the teachings of the U.S.-Pat. No. 2,586,906 Beckett 'e'tal'. i

The valve 120 is, itself, pressure controlled by air pressure at its opposite ends. and. includes internal restrictors 120a spool. Thus, if:either .spool end is exhausted, the spool ofthe valve 120 will shift toward that end due to the-pressure drop across the associated restrictorfAccordingly,the valve may readily be controlled by normallyjclosed;two-position pilot valves 125 connected to each end of the valve 120. x

One pilot valve 125 is used for each of the blades. and each of the valves is adjustably positioned-on one of the housing sidewalls to be engaged only when its associated arm is in a desired opened position! One valve IZSd '(FIG. 2 is 'positioned on the wall 17 to' be? engaged by an actuator rod I28 forming an extension of the'arm 32 when the bla'de'30 is in a predetermined opened position. resulting in the dumping of which apply air under line pressure to'each of the ends of the" i I pressure from one side of the valve 120 and the shifting of its associated spool with the reversal of application of air pressure to the'piston motors 50. The reverse action occurs when the arm 42a engages the pilot valve [251: (FIG. 3). Valve I25b may be adjustably mounted on wall 16,. and defines the desired open position of the blade 40.

The pneumatic diagram of FIG. I0 is one in which the valve of this invention will be caused to be cycled in a fully automatic manner as depicted by the views of FIGS. 4. Sand 6. As shown in FIG. 4. the valve 10 is positioned in flow controlling relation in a conduit 150 for metering, or controlling the discharge of material while maintaining an air lock. if desired. The upper blade 30 is in the open position and the lower blade 40 is in the closed position, resulting in material being admitted into. the interior of the 'valve. Retracting movement of the motors 50 first results in the closing of the upper blade 30 (FIG. 5) by reason of the superior force of the springs until the upper blade can close no further. Continued retracting movement of the pistons 50 opens the lower blade 40 (F IG. 6) until the'arms 42 engage pilot valve l25b. This results in the shifting of the'sp'ool within the valve I20.- the reversal of air pressure to the motors 50. and the reversal in the sequence of operation depicted in FIGS. 4. S and 6 until the position of the mechanical stop. and the cycle will then continue until the valve IZSb is tripped followed by the opening of the blade 30 permitting the obstacle'to drop through. The pair of balanced fluid niotors'50 in common with each of the blades and associated arms provides equalized forces to each blade. and results ina unit which is reliable and which is low in cost. A

single two-position control valve. with only two pilotvalves is effective-to provide fully automatic operation withlow power requirements and low maintenance cost. and freedom from electrical hazards.

While the formof. apparatus herein described constitutes a preferred embodiment of this invention, it is to=be understood that this invention isnot limited to this precise formof apparatus. and that changes may be'inade therein without departing from the scopeof the invention. 2

Iclaim:' 1

I. An air lock gate valve for controlling the flowof particulate flowable material from a first region atone pressure into a second region at a different pressure. comprising an elongated valve housing formed with an inlet adapted to open into said first region; an outlet adapted to open into said second region.

said housing defining an enclosed flow conduit extending between said inlet and said outlet. a pair of curved flow control blades including a first blade proportioned to extend across said housing adjacent said inlet in flow blocking relation to said conduit. means on said housing pivotally mounting said first blade with the concavity thereof opening toward said outlet and providing for movement thereof into said flow blocking position and into a retracted flow permitting position. and a second curved blade proportional to extend across said housing adjacent said outlet in flow blocking relation to said conduit, means on said housing pivotally mounting said second blade with the concavity thereof facing toward said inlet and providing for movement thereof between its said flow blocking position and a retracted flow permitting position for discharging the contents of said conduit stored between said blades, said blades having actuating lever means. a linearly acting motor having two ends each connected to one of said lever means and movable in one'direction to urge said second blade into its flow. blocking position and simultaneously to cause the first blade to'move into its said flow pen blocking positions blade closes first and opens last with respect to movement of said second blade.

2. The valve of claim 1 in which said motor means includes a piston motor having its opposite ends connected to apply an opening force to one of said blades and simultaneously a closing force to the other of said blades.

3, The valve of claim 2 in which said first blade is spring biased to a closed position with a sufficient force to assure that its blade closes before said second blade opens.

4. The valve of claim 2 in which said motor means further includes a two-position valve operable selectively to apply fluid pressure to said piston motor to effect alternate opening and closing of said valve blades. and a pair of control valves responsive to the movement of said blades into their respective retracted positions and connected in controlling relation to said two-position valve to reverse the position thereof in response to the movement of either one of said blades into its said retracted position.

5. The valve of claim 5 in which said two-position valve defines an exhaust port through which fluid pressure from said piston motor exhausts during movement thereof. and adjustable fluid pressure relief means associated with said exhaust port for controlling the rate of movement of said blades by controlling the rate of fluid exhaust from said piston motor.

6. A valve for controlling and measuring the flow of partic ulatc flowable material, comprising a valve housing rectangular in section and having an inlet at one end and an outlet at the other end thereof and defining a flow conduit therebetween, a

pair of spaced-apart flow control blades each being mounted on said housing and being proportioned to extend through one wall of said housing across said conduit in flow blocking relation thereto with an upper one of said blades being positioned adjacent said inlet and the lower one of said blades being positioned adjacent said outlet and defining therebetween in the flow blocking position thereof a space of predetermined volume, separate lever means being pivotally mounted external of said housing and connected to each of said blades providing for movement of said blades between said flowand a flow-permitting position. bidirectional linear motor external of said housing having two ends each connected to one of said lever means and being operable upon movement thereof in one direction to urge said lower blade toward its said flow blocking position and simultaneously to cause the upper blade to move toward its flow permitting position, and upon reversal thereof first to move said upper blade to its closed position then to urge said upper blade into its closed position while moving said lower blade into its said open position, and bias means to assure that the upper blade closes first and opens last with respect to movement of said blades.

7 7. The valve of claim 6 in which said one housing wall is provided with a slot for each of said plates, and flexible seal strips mounted on said one wall outer surface adjacent each of said slots and extending through the associated said slot into said housingin overlying relation to the outer surfaces of the associated said blade.

8 The valve of claim 7 further including further flexible seal stripsmounted exteriorly of said housing at each of said slots,

there being a pair of said further seal strips for each of said blades .in which the strips of each said pair are mounted respectively above and beneath an associated said blade and have portions extending outwardly in overlying relation to said blade upper and lower surfaces, and means on said housing one wall extending outwardly away from each said slot at the .ends thereof and engaging the ends of said further seal strips '-;;f0r forming with said blade an and said seal strips a complete seals having lower surfaces proportioned to engage the upper surface of the said lower blade in the said closed position thereof. v,

10 An air lock valve for controlling the flow of particulate material comprising, an elongated valve housing being generally rectangular in cro cction'and having an inlet, an outlet and a flow passage t -h rbetweeh. a pair or curbed curved blades each being pii/o tal l'y mounted on said housing and each being proportionedto extend through one sidewall of said housing into flow blodkingr ela'tion to said passage including an upper blade adjacent 'said inlet with the concavity thereof opening downwardly and a lower blade adjacent said outlet with the concavity thereof opening upwardly toward said upper blade and defining with said upper blade a space in said housing of predetermined volume. and motor control means interconnecting said blades and providing for alternate movement thereof between flow permitting and flow'blocking positions with respect to said passage including a piston motor with one end of said piston motor being connected between one of said blades and its associated pivot point and the other end thereof connected to rotate the other of said blades at a position outwardly of said other blades pivot point for applying an opening force to one of said blades simultaneously applying a closing force to the other of said blades.

ll. An air lock metering valve adapted to receive flowable dry particulate material from a first pressure region and to transmit a measured quantity of such'material to a second pressure region, comprising a generally tubularvalve body having an inlet adapted for connection to said first pressure re- -gion and an outlet spaced from said inlet adapted for connection to said second pressure region, avalve blade pivotally movable transversely of said body into flow blocking relation to said inlet, a second valve blade pivotally movable transversely of said body into flow blocking relation to said outlet and defining with said first blade an enclosed region in said housing adapted to receive said quantity of material, bidirectional linear actuator means having one end connected in driving relation to one of said blades and having an opposite end connected in driving relation to the other of said blades so that movement of said actuator applies an opening force to one blade and a closing force to the other blade. and bias means urging said first blade into the flow blocking position to assure that it closes prior to the opening of the second blade and remains closed until said second blade is returned to its flow blocking position by said linear actuator.

12. A jam-proof automatic flow control valve for measuring quantities of flowable bulk material comprising a valve housing defining a section of conduit having an inlet at one end and an outlet at the other end, a first valve blade adjacent said inlet and movable across said conduit and into a closed flow blocking position an and into an open retracted flow permitting position, a second valve blade adjacent said outlet and movable across said conduit into closed flow-blocking and open flowpermitting positions, and in its said flow-blocking position defining with said first blade a space in said conduit for receiving a quantity of said material, a bidirectional fluid pressure operated linear actuator having one end connected in driving relation to said first blade and having another end connected in driving relation to said second blade so that movement of said actuator in either of its two directions applies an opening force to one of said blades and a closing force to the other of said blades, bias means urging said first blade into its flow-blocking position to assure that it closes prior to the opening of said second blade and remains closed until said second blade is returned to its flow-blocking position by said actuator, a fluid control valve operable selectively to apply fluid pressure to said actuator to effect alternate opening and closing movements of said valve blades, and a pair of pilot valves one for each of said blades connected to control said control valve and each positioned to be responsive to the movement of its respective blade only into its open flow permitting position so that a temporary blockage in said conduit preventing the closing of either of said blades does not inter- I rupt the automatic operation of said flow control valve.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 34 I 35 Dated Iannan: 1 2 1 1 lnv n fl George W. Armstronq It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 53, "opposites" should be -opposite--.

Column 2, line 72, delete "portions" Column 3, line 57, "pivotal" should be pivoted Column 7, line 19, "claim 5" should be -claim 4.

Column 7, line 68, "an" should be deleted.

Column 8, line 7, "curbed" should be deleted.

Column 8 line 52, delete "an" first occurrence Signed and sealed this 28th day of September 1971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROB GOTTSCHALK Attesting Officer Acting Commissioner of Pa 

1. An air lock gate valve for controlling the flow of particulate flowable material from a first region at one pressure into a second region at a different pressure, comprising an elongated valve housing formed with an inlet adapted to open into said first region, an outlet adapted to open into said second region, said housing defining an enclosed flow conduit extending between said inlet and said outlet, a pair of curved flow control blades including a first blade proportioned to extend across said housing adjacent said inlet in flow blocking relation to said conduit, means on said housing pivotally mounting said first blade with the concavity thereof opening toward said outlet and providing for movement thereof into said flow blocking position and into a retracted flow permitting position, and a second curved blade proportional to extend across said housing adjacent said outlet in flow blocking relation to said conduit, means on said housing pivotally mounting said second blade with the concavity thereof facing toward said inlet and providing for movement thereof between its said flow blocking position and a retracted flow permitting position for discharging the contents of said conduit stored between said blades, said blades having actuating lever means, a linearly acting motor having two ends each connected to one of said lever means and movable in one direction to urge said second blade into its flow blocking position and simultaneously to cause the first blade to move into its said flow permitting position for admitting material from said first region into said housing conduit, and movable in a second direction to return said first blade to its flow blocking position and with continued movement to move said second blade into its flow permitting position to empty the contents of said conduit into said second region, and bias means to assure that said first blade closes first and opens last with respect to movement of said second blade.
 2. The valve of claim 1 in which said motor means includes a piston motor having its opposite ends connected to apply an opening force to one of said blades and simultaneously a closing force to the other of said blades.
 3. The valve of claim 2 in which said first blade is spring biased to a closed position with a sufficient force to assure that its blade closes before said second blade opens.
 4. The valve of claim 2 in which said motor means further includes a two-position valve operable selectively to apply fluid pressure to said piston motor to effect alternate opening and closing of said valve blades, and a pair of control valves responsive to the movement of said blades into their respective retracted positions and connected in controlling relation to said two-position valve to reverse the position thereof in response to the movement of either one of said blades into its said retracted position.
 5. The valve of claim 5 in which said two-position valve defines an exhaust port through which fluid pressure from said piston motor exhausts during movement thereof, and adjustable fluid pressure relief means associated with said exhaust port for controlling the rate of movement of said blades by controlling the rate of fluid exhaust from said piston motor.
 6. A valve for controlling and measuring the flow of particulate flowable material, comprising a valve housing rectangular in section and having an inlet at one end and an outlet at the other end thereof and defining a flow conduit therebetween, a pair of spaced-apart flow control blades each being mounted on said housing And being proportioned to extend through one wall of said housing across said conduit in flow blocking relation thereto with an upper one of said blades being positioned adjacent said inlet and the lower one of said blades being positioned adjacent said outlet and defining therebetween in the flow blocking position thereof a space of predetermined volume, separate lever means being pivotally mounted external of said housing and connected to each of said blades providing for movement of said blades between said flow-blocking positions and a flow-permitting position, bidirectional linear motor external of said housing having two ends each connected to one of said lever means and being operable upon movement thereof in one direction to urge said lower blade toward its said flow blocking position and simultaneously to cause the upper blade to move toward its flow permitting position, and upon reversal thereof first to move said upper blade to its closed position then to urge said upper blade into its closed position while moving said lower blade into its said open position, and bias means to assure that the upper blade closes first and opens last with respect to movement of said blades.
 7. The valve of claim 6 in which said one housing wall is provided with a slot for each of said plates, and flexible seal strips mounted on said one wall outer surface adjacent each of said slots and extending through the associated said slot into said housing in overlying relation to the outer surfaces of the associated said blade.
 8. The valve of claim 7 further including further flexible seal strips mounted exteriorly of said housing at each of said slots, there being a pair of said further seal strips for each of said blades in which the strips of each said pair are mounted respectively above and beneath an associated said blade and have portions extending outwardly in overlying relation to said blade upper and lower surfaces, and means on said housing one wall extending outwardly away from each said slot at the ends thereof and engaging the ends of said further seal strips for forming with said blade an and said seal strips a complete air lock at said slot.
 9. The valve of claim 6 further including arcuate blade seals there being a pair of such arcuate seals for each of said blades received in said housing including an upper seal pair mounted on the inside walls of said housing and having lower surfaces proportioned to engage the upper surface of said upper blade in the closed position thereof and a further said pair of blade seals having lower surfaces proportioned to engage the upper surface of the said lower blade in the said closed position thereof.
 10. An air lock valve for controlling the flow of particulate material comprising, an elongated valve housing being generally rectangular in cross section and having an inlet, an outlet and a flow passage therebetween, a pair or curbed curved blades each being pivotally mounted on said housing and each being proportioned to extend through one sidewall of said housing into flow blocking relation to said passage including an upper blade adjacent said inlet with the concavity thereof opening downwardly and a lower blade adjacent said outlet with the concavity thereof opening upwardly toward said upper blade and defining with said upper blade a space in said housing of predetermined volume, and motor control means interconnecting said blades and providing for alternate movement thereof between flow permitting and flow blocking positions with respect to said passage including a piston motor with one end of said piston motor being connected between one of said blades and its associated pivot point and the other end thereof connected to rotate the other of said blades at a position outwardly of said other blades pivot point for applying an opening force to one of said blades simultaneously applying a closing force to the other of said blades.
 11. An air lock metering valve adapted to receive flowable dry particulate material frOm a first pressure region and to transmit a measured quantity of such material to a second pressure region, comprising a generally tubular valve body having an inlet adapted for connection to said first pressure region and an outlet spaced from said inlet adapted for connection to said second pressure region, a valve blade pivotally movable transversely of said body into flow blocking relation to said inlet, a second valve blade pivotally movable transversely of said body into flow blocking relation to said outlet and defining with said first blade an enclosed region in said housing adapted to receive said quantity of material, bidirectional linear actuator means having one end connected in driving relation to one of said blades and having an opposite end connected in driving relation to the other of said blades so that movement of said actuator applies an opening force to one blade and a closing force to the other blade, and bias means urging said first blade into the flow blocking position to assure that it closes prior to the opening of the second blade and remains closed until said second blade is returned to its flow blocking position by said linear actuator.
 12. A jam-proof automatic flow control valve for measuring quantities of flowable bulk material comprising a valve housing defining a section of conduit having an inlet at one end and an outlet at the other end, a first valve blade adjacent said inlet and movable across said conduit and into a closed flow blocking position an and into an open retracted flow permitting position, a second valve blade adjacent said outlet and movable across said conduit into closed flow-blocking and open flow-permitting positions, and in its said flow-blocking position defining with said first blade a space in said conduit for receiving a quantity of said material, a bidirectional fluid pressure operated linear actuator having one end connected in driving relation to said first blade and having another end connected in driving relation to said second blade so that movement of said actuator in either of its two directions applies an opening force to one of said blades and a closing force to the other of said blades, bias means urging said first blade into its flow-blocking position to assure that it closes prior to the opening of said second blade and remains closed until said second blade is returned to its flow-blocking position by said actuator, a fluid control valve operable selectively to apply fluid pressure to said actuator to effect alternate opening and closing movements of said valve blades, and a pair of pilot valves one for each of said blades connected to control said control valve and each positioned to be responsive to the movement of its respective blade only into its open flow permitting position so that a temporary blockage in said conduit preventing the closing of either of said blades does not interrupt the automatic operation of said flow control valve. 